Evidence for single electron transfer in the reduction of alcoholswith lithium aluminum hydride

EPR evidence supporting a single electron transfer mechanism in the reduction of secondary and tertiary alcohols to hydrocarbons with LiAlH₄ is presented.     

Nonnegative mth roots of nonnegative 0-symmetric idempotent matrices

Nonnegative mth roots of nonnegative 0-symmetric idempotent matrices have been characterized. As an application, a characterization of nonnegative matrices A whose Moore-Penrose generalized inverse A² is some power of A is obtained, thus yielding some well-known theorems.     

Experimental study of the variation of the plasma temperature with the laser flux

Experiments performed with a 50 MW — 60 nsec ruby laser to estimate the temperature of the plasma produced on the planar targets of carbon as well as polyethylene are reported. Temperatures were estimated by two foil ratio technique. The temperatures of carbon and polyethylene plasma show aφ ^2/9 dependance on flux in the flux regime of 10¹⁰ W/cm² to 5 × 10¹¹ W/cm². The comparatively slower dependance is explained on the basis of purely collisional absorption, the effect being enhanced due to relatively long duration of the laser pulses. Scaling laws of plasma temperature against laser flux obtained by different workers in different flux regimes have been analysed on the basis of collisional and non-collisional absorption.     

Electroproduction of η mesons in the region of the resonances S11(1535)

We report on an experiment on electroproduction in the resonance region in the mass range 1505 ? W ? 1715 MeV. Data have been taken at q² = 0. 22, 0.6 and 1 GeV². The angular distributions obtained support that η production proceeds mainly through S-wave excitation due to the resonance S₁₁(1535).The total cross section of the formation of this resonance decreases much more slowly with increasing momentum transfer than the total ep cross section.     

Iron (III) complexation with 2,3-pyridinediol

Iron(III) complexation with 2,3-pyridinediol has been investigated with a view to ascertaining the structures of the complexes formed and examining the analytical potential of this biochemically important ligand.     

Multiresidue analysis and probabilistic dietary risk assessment of 241 pesticides in wheatgrass (Triticum sp.) using LC–MS/MS in combination with QuEChERS extraction

Wheatgrass is consumed as an important nutritious herbal food supplement across the globe; however, limited studies have been reported analyzing multiclass pesticides in this complex, nutrient-rich natural product. An analytical method was developed for the estimation of 241 pesticides in random wheatgrass samples collected from Delhi Northern Capital Region (Delhi-NCR). Extraction was performed by QuEChERS, cleaning was performed by dispersive solid-phase extraction and the extracts were analyzed using triple quadrupole liquid chromatography mass spectrometry. The limit of quantification was 0.5 μg/kg, which is well below the European Union Maximum Residue Level. The coefficient of determination was >0.991 across a calibration range of 0.5–100 μg/kg. The relative standard deviation values for 231 pesticides based on 10 replicates of samples spiked at 10 μg/kg were <5%. Among random samples, 54% confirmed the presence of at least one pesticide. The results indicated the presence of eight different pesticides among 38% of the total population with metribuzin at 299.7 μg/kg and carfentrazone-ethyl at 19.47 μg/kg exceeding the permissible limits among 6% of the total estimated population. The chronic and acute risk quotients as calculated were <1, indicating nonsignificant dietary risk to consumers. However, the presence of pesticides above the permissible limit is likely to result in adverse health effects to the consumers of herbal supplements from an urban population and incorporating measures would be useful to ensure the quality and safety of wheatgrass consumption.